1995 JEEP YJ differential

LUBRICANT LEVEL
Determine the axle differential housing lubricant
level according to the following procedure.
(1) Raise and support the vehicle.
(2) Remove the fill-hole plug (Fig. 6 and 7) from
the axle differential housing cover. The gear lubri-
cant should be 13 mm (1/2 inch) below the bottom
edge of the fill hole.
(3) If not acceptable, raise the lubricant level to 13
mm (1/2 inch) below the bottom edge of the fill hole.
Add lubricant in small amounts to raise the
level.
(4) Install the fill-hole plug in the differential
housing cover. Tighten the plug with 34 NÉm (25 ft.
lbs.) torque.
(5) Remove the support and lower the vehicle.
LUBRICANT CHANGE
When it becomes necessary to change the axle lu-
bricant in a Jeep front or rear axle, use the following
procedure.
(1) Raise and support the vehicle.(2) Place a container under the axle differential
housing.
(3) Remove the axle differential housing cover
bolts. Remove the housing cover.
(4) Allow the axle gear lubricant to completely
drain into the container.
CAUTION: Do not flush a rear axle Trac-Lok differ-
ential. Trac-Lok differentials may be cleaned only by
disassembling the unit and wiping the components
with clean, lint-free cloth.
(5) Flush the inside of the differential housing
with a flushing oil.Do not use water, steam, ker-
osene or gasoline for flushing.
(6) Remove any residual RTV sealant/gasket mate-
rial from the differential housing and cover. Thor-
oughly clean the contact surfaces with mineral spirits
and dry the surfaces completely.
(7) Apply a bead of MOPAR RTV Sealant, or an
equivalent sealant, around the bolt circle on the
housing and on the cover (Fig. 8).
If differential housing cover is not installed
within 20 minutes after applying sealant, the
sealant must be removed and another bead ap-
plied.
(8) Install the cover on the differential housing
with the attaching bolts (Fig. 9). Tighten the cover
bolts with 47 Nzm (35 ft. lbs.) torque.
(9) Remove the fill-hole plug and add the replace-
ment gear lubricant to the differential housing. Refer
to Specifications above.
(10) Install the fill-hole plug. Tighten the plug
with 34 NÉm (25 ft. lbs.) torque.
Fig. 6 Rear AxleÐTypical
Fig. 7 Front Axle (4WD)ÐTypical
Fig. 8 RTV Sealant ApplicationÐTypical
JLUBRICATION AND MAINTENANCE 0 - 25

(11) Remove the support and lower the vehicle.
DRIVE SHAFTS
Lubricate at the intervals described in the Mainte-
nance Schedule section of this Group. Refer to Group
16, Propeller Shafts for proper service procedures.
CAUTION: It is very important that drive shafts be
lubricated at periodic intervals and that the speci-
fied type of lubricant be used. Failure to properly
lubricate could result in premature wear of drive
shaft components.
LUBRICANT SPECIFICATION
Use Mopar, Multi-purpose Grease or any lubricate
that is identified as NLGI GC-LB lubricant.
RUBBER AND PLASTIC HOSES/TUBING
The condition of underbody rubber hose and plastic
tubing should be inspected whenever underbody ser-
vice is performed.
Rubber hoses and plastic tubing should be re-
placed immediately if there is any evidence of
failure.
HOSE/TUBING INSPECTION
(1) Inspect all hose and tubing fittings for loose-
ness and corrosion. Inspect the rubber hoses for brit-
tleness and cracks. Thoroughly inspect the hose ends
(those that are slipped over nipple connectors) for
splits (Fig. 10, 11, 12, 13, 14, 15 and 16).
(2) Inspect the surface of hoses and tubing for heat
and mechanical damage. Hose and tubing located
close to an exhaust pipe should be given special at-
tention.
(3) Inspect the rubber hose routing to ensure that
the hoses do not contact any heat source, moving
component, etc., that would potentially cause heat or
mechanical damage.
(4) Inspect all the hose connections to ensure that
they are secure and there is no fluid leakage. Actual
dripping of hot fluid should be noted and the clamps
tightened in an attempt to stop the leakage before re-
placing the hose.
Fig. 10 Front Axle Vent Hose (4WD)ÐXJ Vehicles
Fig. 9 Differential Housing Cover Installed
Fig. 11 Front Axle Vent HoseÐYJ Vehicles
0 - 26 LUBRICATION AND MAINTENANCEJ

CHASSIS AND BODY COMPONENTS
INDEX
page page
Body Components........................ 32
Chassis Component and Wheel Bearing
Lubricants............................. 28
Front Wheel Bearings...................... 28
Headlamps.............................. 33
Manual Steering Gear...................... 30Power Brake System....................... 30
Power Steering System..................... 29
Speedometer Cable....................... 33
Steering Linkage.......................... 28
Tires................................... 32
CHASSIS COMPONENT AND WHEEL BEARING
LUBRICANTS
The chassis component and wheel bearing lubri-
cants that are recommended for Jeep vehicles are
identified by the NLGI Certification Symbol (Fig. 1).
The symbol contains a coded designation that identi-
fies the usage and quality of the lubricant.
The letterGdesignates wheel bearing lubricant.
LetterLdesignates chassis lubricant. When the let-
ters are combined the lubricant can be used for dual
applications. The suffix lettersCandBdesignate the
level of the lubricant for the application. The letterC
represents level available for wheel bearing lubricant
(G) and the letterBrepresents level available for
chassis lubricant (L).
STEERING LINKAGE
The steering linkage (Fig. 2) should be lubricated
and inspected at the intervals described in the Main-
tenance Schedules section of this Group. Refer to
Group 2, Front Suspension and Axles for proper ser-
vice procedures.
LUBRICANT SPECIFICATION
Use Mopar, Multi-purpose Grease or NLGI GC-LB
lubricant equivalent to lubricate the steering linkage.
INSPECTION
(1) Inspect the steering linkage. Examine the tie
rods and the drag link for bending, and the ball
studs for looseness and excessive wear.(2) Replace, as necessary, all torn/ruptured ball-
stud seals and damaged/defective steering linkage
components.
CAUTION: Use care to prevent lubricant from con-
tacting the brake rotors.
FRONT WHEEL BEARINGS
Some 2WD XJ vehicles are equipped with service-
able front wheel bearings. XJ 4WD vehicles have
semi-floating axle shafts and axle shaft bearings that
are lubricated via differential lube oil.
RECOMMENDED MAINTENANCEÐ2WD XJ
VEHICLES
If equipped, the serviceable front wheel bearings
should be lubricated (re-packed) at the same time as
front brake pad/caliper service is conducted.
LUBRICANT SPECIFICATION
Wheel bearings should be lubricated with a lubri-
cant that is identified as NLGI GC-LB lubricant.
INSPECTION/LUBRICATION
(1) Remove the wheel/tire and the disc brake cali-
per.Do not disconnect the caliper brake fluid
Fig. 1 NLGI Lubricant Container Certification/
Identification Symbol
Fig. 2 Steering Components (XJ)ÐTypical
0 - 28 LUBRICATION AND MAINTENANCEJ

(5) Inspect the reservoir rubber diaphragm seal for
cracks, cuts and distortion.
(6) Inspect the brake fluid tubing fittings and the
master cylinder housing for indications of fluid leak-
age. Repair as necessary.
(7) Install the brake fluid reservoir cover.
ANTI-LOCK BRAKE SYSTEMÐXJ VEHICLES
The anti-lock brake system fluid reservoir for XJ
Vehicles is located in the engine compartment at the
left side of the dash panel.
(1) Turn the ignition switch ON and allow the
pump motor to operate until it automatically de-en-
ergizes.
(2) Clean the cover before removing it.
CAUTION: Over-filling could cause fluid overflow
and possible reservoir damage when the pump mo-
tor energizes.
(3) The brake fluid level should be no lower than
the ADD indicator on the side of the reservoir (Fig.
8). If not, add brake fluid as necessary. Raise the
fluid level to the FULL indicator only. Do not over-fill
the reservoir.
(4) Turn the ignition switch OFF.
BRAKE SYSTEM INSPECTION
A brake system inspection should be included with
all brake service procedures, and also each time the
vehicle is lubricated.
(1) Inspect the brake pads and linings for excessive
wear, cracks, charred surfaces and broken rivets.
(2) Inspect brake pads and linings for contamina-
tion from brake fluid, and/or other fluids.
(3) Replace the brake pads linings if they are worn
to within 0.78 mm (1/32 in) of the rivet head.
(4) Operate the rear brake self-adjuster lever and
pivot. Test the operation of the self-adjuster screw for
ease of movement.
(5) Inspect the self-adjuster components for wear
or damage.
(6) Inspect the disc brake caliper dust boot for
damage and indications of brake fluid leakage. In-
spect the bushings and pins for corrosion, tears and a
binding condition.
(7) Pull the rear wheel cylinder dust boot back to
expose the wheel cylinder housing. Inspect for fluid
leaks. Inspect the pistons and cylinder bores.
(8) Inspect the brake differential warning valve
and housing for indications of leakage.
BRAKE FLUID HOSES/TUBING
The rubber brake fluid hoses should be inspected
for:
²Correct length
²Severe surface cracking
²Swelling
²Pulling
²Scuffing
²Excessively worn areas
If the hose has cracks or abrasions in the rub-
ber cover, the hose should be replaced.
(1) Inspect all the hoses for kinks, a distorted con-
dition and fluid leakage.
(2) Inspect the hose and tubing routing under the
vehicle. Verify that no hose/tubing is rubbing against
any exhaust or other underbody components.
PARKING BRAKE
(1) Engage the parking brake pedal and then re-
lease it.
(2) Test it for smooth operation and vehicle-holding
capability.
(3) Inspect the parking brake cables.
(4) With the parking brake released, the rear
wheels should
rotate without restriction. Adjust the parking brake
cable tension, if necessary (Fig. 9 and 10).
(5) Repair any parking brake malfunctions.
BRAKE OPERATIONAL TEST
(1) Drive the vehicle and test for proper brake ac-
tion.
Fig. 7 Reservoir Fluid LevelÐYJ (2.5L)
Fig. 8 Reservoir Fluid LevelÐYJ-XJ and Anti-Lock
Brake System
JLUBRICATION AND MAINTENANCE 0 - 31

spring and axle travel (jounce or rebound) is limited
through use of rubber bumpers mounted on the
frame.
Suspension components which use rubber bushings
should be tightened at vehicle ride height. This will
prevent premature failure of the bushing and main-
tain ride comfort. The bushings should never be lu-
bricated.
The shocks absorbers dampen jounce and rebound
of the vehicle over various road conditions. The top of
the shock absorbers bolt to the frame. The bottom of
the shocks bolt to the axle brackets.
The stabilizer bar is used to minimize vehicle front
sway during turns. The spring steel bar helps control
vehicle body in relationship to the suspension move-
ment. The bar extends across the front underside of
the chassis and connects to the frame rails. Links
connect the bar to the axle brackets. Stabilizer bar
mounts are isolated by rubber bushings.
The track bar is used to minimize front axle side-
to-side movement. The track bar is attached to a
frame rail bracket and axle bracket. The bar uses
bushings at both ends.
FRONT DRIVE AXLE
It is not necessary to remove the complete axle
from the vehicle for routine differential service. If the
differential housing or axle shaft tubes are damaged,
the complete axle assembly can be removed and ser-
viced.
For complete drive axle assembly removal and in-
stallation refer to Drive Axle Assembly Replacement
in this Group.
The removable cover provides for servicing without
removing axle from vehicle.
The integral type housing, hypoid gear design has
the centerline of the pinion set above the centerline
of the ring gear.
The Model 30 axle has the assembly part number
and gear ratio listed on a tag. The tag is attached to
the housing cover (Fig. 4). Build date identification
codes are stamped on the axle shaft tube cover side.
XJ and YJ axles are equipped with an optional
A.B.S. brake system. The A.B.S. tone rings are
pressed onto the axle shaft near the hub and
knuckle. For additional information on the A.B.S.
system refer to Group 5, Brakes.
²XJ vehicles use a non-disconnect axle.
²YJ vehicles use a vacuum disconnect axle (Fig. 5).
STANDARD DIFFERENTIAL OPERATION
The differential gear system divides the torque be-
tween the axle shafts. It allows the axle shafts to ro-
tate at different speeds when turning corners.
Each differential side gear is splined to an axle
shaft. The pinion gears are mounted on a pinion
mate shaft and are free to rotate on the shaft. Thepinion gear is fitted in a bore in the differential case
and is positioned at a right angle to the axle shafts.
In operation, power flow occurs as follows:
²Pinion gear rotates the ring gear
²Ring gear (bolted to the differential case) rotates
the case
²Differential pinion gears (mounted on the pinion
mate shaft in the case) rotate the side gears
²Side gears (splined to the axle shafts) rotate the
shafts
During straight-ahead driving, the differential pin-
ion gears do not rotate on the pinion mate shaft. This
occurs because input torque applied to gears is di-
vided and distributed equally between the two side
gears. As a result, the pinion gears revolve with the
pinion mate shaft but do not rotate around it (Fig. 6).
When turning corners, the outside wheel must
travel a greater distance than the inside wheel. This
difference must be compensated for in order to pre-
vent the wheels from scuffing and skidding through
the turn. To accomplish this, the differential allows
Fig. 4 Model 30 Differential Cover
Fig. 5 Disconnect Feature
JFRONT SUSPENSION AND AXLE 2 - 3

the axle shafts to turn at unequal speeds (Fig. 7). In
this instance, the input torque applied to the pinion
gears is not divided equally. The pinion gears now ro-
tate around the pinion mate shaft in opposite direc-tions. This allows the side gear and axle shaft
attached to the outside wheel to rotate at a faster
speed.
Fig. 6 Differential OperationÐStraight-Ahead Driving
Fig. 7 Differential OperationÐOn Turns
2 - 4 FRONT SUSPENSION AND AXLEJ

AXLE NOISE/VIBRATION DIAGNOSIS
INDEX
page page
Driveline Snap........................... 19
Gear and Bearing Noise.................... 18
General Information....................... 18Low Speed Knock......................... 19
Vibration................................ 19
GENERAL INFORMATION
Axle bearing problem conditions are usually caused
by:
²Insufficient or incorrect lubricant
²Foreign matter/water contamination
²Incorrect bearing preload torque adjustment
²Incorrect backlash (to tight)
When serviced, the bearings must be cleaned thor-
oughly. They should be dried with lint-free shop tow-
els.Never dry bearings with compressed air.
This will overheat them and brinell the bearing
surfaces. This will result in noisy operation af-
ter repair.
Axle gear problem conditions are usually the result
of:
²Insufficient lubrication
²Incorrect or contaminated lubricant
²Overloading (excessive engine torque) or exceeding
vehicle weight capacity
²Incorrect clearance or backlash adjustment
Insufficient lubrication is usually the result of a
housing cover leak. It can also be from worn axle
shaft or pinion gear seals. Check for cracks or porous
areas in the housing or tubes.
Using the wrong lubricant will cause overheating
and gear failure. Gear tooth cracking and bearing
spalling are indicators of this.
Axle component breakage is most often the result
of:
²Severe overloading
²Insufficient lubricant
²Incorrect lubricant
²Improperly tightened components
Overloading occurs when towing heavier than rec-
ommended loads. Component breakage can occur
when the wheels are spun excessively. Incorrect lu-
bricant quantity contributes to breakage. Loose dif-
ferential components can also cause breakage.
Incorrect bearing preload or gear backlash will not
result in component breakage. Mis-adjustment will
produce enough noise to cause service repair before a
failure occurs. If a mis-adjustment condition is not
corrected, component failure can result.
Excessive bearing preload may not be noisy. This
condition will cause high temperature which can re-
sult in bearing failure.
GEAR AND BEARING NOISE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant. Incorrect backlash, tooth contact, or worn/dam-
aged gears can cause noise.
Gear noise usually happens at a specific speed
range. The range is 30 to 40 mph, or above 50 mph.
The noise can also occur during a specific type of
driving condition. These conditions are acceleration,
deceleration, coast, or constant load.
When road testing, accelerate the vehicle to the
speed range where the noise is the greatest. Shift
out-of-gear and coast through the peak-noise range.
If the noise stops or changes greatly, check for insuf-
ficient lubricant. Incorrect ring gear backlash, or
gear damage can cause noise changes.
Differential side and pinion gears can be checked
by turning the vehicle. They usually do not cause
noise in straight-ahead driving. These gears are
loaded during vehicle turns. If noise does occur dur-
ing vehicle turns, the side or pinion gears could be
worn or damaged. A worn pinion gear mate shaft can
also cause a snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion gear bear-
ings can all produce noise when worn or damaged.
Bearing noise can be either a whining, or a growling
sound.
Pinion gear bearings have a constant-pitch noise.
This noise changes only with vehicle speed. Pinion
bearing noise will be higher because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs the pinion rear bearing is
the source of the noise. If the bearing noise is heard
during a coast, front bearing is the source.
Worn, damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing. The pitch of differential
bearing noise is also constant and varies only with
vehicle speed.
2 - 18 FRONT SUSPENSION AND AXLEJ

Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn U-
joint or by worn side-gear thrust washers. A worn
pinion gear shaft bore will also cause low speed
knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by a:
²Damaged drive shaft
²Missing drive shaft balance weight
²Worn, out-of-balance wheels
²Loose wheel lug nuts
²Worn U-joint
²Loose spring U-bolts
²Loose/broken springs
²Damaged axle shaft bearings
²Loose pinion gear nut
²Excessive pinion yoke run out²Bent axle shaft
Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rear-end vi-
bration. Do not overlook engine accessories, brackets
and drive belts.
All driveline components should be examined be-
fore starting any repair.
Refer to Group 22ÐTires And Wheels for addi-
tional information involving vibration diagnosis.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by:
²High engine idle speed
²Loose engine/transmission/transfer case mounts
²Worn U-joints
²Loose spring mounts
²Loose pinion gear nut and yoke
²Excessive ring gear backlash
²Excessive differential side gear-to-case clearance
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the ve-
hicle on a hoist with the wheels free to rotate.
Instruct the helper to shift the transmission into
gear. Listen for the noise, a mechanics stethoscope is
helpful in isolating the source of a noise.
JFRONT SUSPENSION AND AXLE 2 - 19